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Sensor for Direct Measurement of the Boundary Shear Stress in Fluid FlowThe formation of scour patterns at bridge piers is driven by the forces at the boundary of the water flow. In most experimental scour studies, indirect processes have been applied to estimate the shear and normal stress using measured velocity profiles. The estimations are based on theoretical models and associated assumptions. However, the turbulence flow fields and boundary layer in the pier-scour region are very complex. In addition, available turbulence models cannot account accurately for the bed roughness effect. Direct measurement of the boundary shear and normal stress and their fluctuations are attractive alternatives. However, this approach is a challenging one especially for high spatial resolution and high fidelity measurements. The authors designed and fabricated a prototype miniature shear stress sensor including an EDM machined floating plate and a high-resolution laser optical encoder. Tests were performed both in air as well as operation in water with controlled flow. The sensor sensitivity, stability and signal-to-noise level were measured and evaluated. The detailed test results and a discussion of future work will be presented in this paper.
Document ID
20150005809
Acquisition Source
Jet Propulsion Laboratory
Document Type
Conference Proceedings
Authors
Bao, Xiaoqi
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Badescu, Mircea
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Bar-Cohen, Yoseph
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Lih, Shyh-Shiuh
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Sherrit, Stewart
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Chang, Zensheu
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Chen, Beck
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Widholm, Scott
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Ostlund, Patrick
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Date Acquired
April 17, 2015
Publication Date
March 7, 2011
Publication Information
Publication: Proceedings SPIE 7981, Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2011
Volume: 7981
Subject Category
Fluid Mechanics And Thermodynamics
Meeting Information
Meeting: Annual International Symposium on Smart Structures/NDE
Location: San Diego, CA
Country: United States
Start Date: March 7, 2011
End Date: March 10, 2011
Sponsors: American Society of Mechanical Engineers, International Society for Optical Engineering
Funding Number(s)
TASK: Task #82-13107
Distribution Limits
Public
Copyright
Other
Keywords
shear stress
sensor
fluid flow

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